VP 5.0L SX port riser hot to touch

[harojs]

Thanks AD, good to know flapper life. Yeah, the VP flapper bulletin says I can remove the flappers on my 1995 VP 5.0L, but man, what if that directive is wrong in reality for my case ...

 

[USA_boater]

I notice on the trailer if I use muffs the water exiting the boat gets much hotter than if I hook up the garden hose to the spigot inside the engine compartment. Not sure what year Volvo began adding that but I feel better using the engine spigot vs the muffs for general maintenance. I will say that if I am concerned about cooling, I like to test it both ways because if it cools with muffs then I know it will cool since I think the spigot is a more accurate representation of in-the-water (theory being that in-the-water would cool better than muffs as you have already pondered).

I also tried the dual hose muffs and did not prefer them. For single muffs, I always put the hose hookup side of the muffs on the port side of the lower unit.

 

[Lou C]

That makes sense as the Volvo impeller is elevated and far forward of the water intakes on the drive. You always lose some water with muffs, whereas running it on the spigot attachment you are getting 100% of the volume of water flow.
I have found that the dual inlet muffs made recently are using a stiffer rubber that does not seem to seal well. I switched to the Mercruiser/Quicksilver single inlet muffs with the clamp and they seal and work much better. Highly recommended.

 

[harojs]

Good stuff. I noticed today when on muffs, if I increased rpm to about 1200, the riser temps started to balance out. One was 85F and the other was 120F. The 120F got down to about 95F.

This tells me the muff method probably does not provide enough flow at idle on the VP 5.0L/SX causing one riser to always be hotter. Only good way to test is with boat in the water. I will give the Mercruiser muffs a try though ...

 

[bruceb58]

Good stuff. I noticed today when on muffs, if I increased rpm to about 1200, the riser temps started to balance out. One was 85F and the other was 120F. The 120F got down to about 95F.

This tells me the muff method probably does not provide enough flow at idle on the VP 5.0L/SX causing one riser to always be hotter. Only good way to test is with boat in the water. I will give the Mercruiser muffs a try though ...

If your Volvo has the screens in it...like it should...you won't be able to use those Mercruiser muffs.

I always use muffs that feed water to both sides on my Volvo. Seem to work the best.

 

[Lou C]

I used to have success with the dual inlet muffs but whoever makes them now, is using very stiff rubber in the cups which does not seal well enough. The Merc muffs are much more flexible. If you can't use the one with the wire clamp, then see if they make a version that just uses the bracket as the clamp, the main thing is the rubber has to conform to the shape of the lower gear housing or else your impeller will be starved for water. With the Volvo impeller being so far up on the engine, it is harder for it to prime than an Alpha with the impeller right above the water intakes, or the Cobra with it in the upper gear housing.

I used to have the plastic screen in the water passage and I had chronic problems with barnacles growing on it, and due to the design (really the same as the Johnson/Evinrude outboard gear case) being inappropriate for a boat moored in salt water I just removed it. That was about 4 seasons ago and I have not had any problems due to removing it, in fact the engine runs consistently cooler due to the wide open intake holes. BTW, some Volvos do not have screens and Mercs don't either but they had more and smaller holes, than the Cobra which has 4 large ones.
The later OMC lower gearcases had a better design with removeable water screens. If I had a problem with sucking up stuff I'd probably try to adapt that to mine but in my use, it has not been an issue.

 

[USA_boater]

Camco makes an adapter for Volvos that hooks up directly to the water intake hose for using their winterization tank system. They specifically warn you in their manual not to use their system on a Volvo with the engine-mounted impeller without using their adapter (don't use the lower unit method)I didn't need to buy the adapter because my Volvo has the engine inlet from the factory.

My story on muffs: Got my boat used in July, ran on trailer with DUAL muffs and I agree with the previous guy who commented they leak too much and were clumsy to use. Exchanged them for a set of single muffs. I did not notice much difference between the temp gauge on the single vs. the dual BUT on either muffs, the exit water was much hotter and the temp gauge was hotter thank if I used the OEM water inlet. It didn't overheat or anything, but I won't be using muffs again unless I see some unique reason at sometime in the future. Otherwise the engine-bay water inlet works as intended.

On my bass boat, the new Merc fourstroke also has a hose inlet on the back of the motor so I sorta wish I'd never bought any muffs LOL. I guess if I ever help my buddy with his '99 alpha drive at least I will have them.

 

[alldodge]

Muffs will never supply the same amount of water that the engine pump can move. I'll leave it to the VP guys for what works best, but I use the dual feed ears on Bravo's and have no issues (hose water pressure at 80 psi)

 

[bruceb58]

BTW, some Volvos do not have screens

Only if they take them out!!!! I have always seen screens in every Volvo SX drive I have come across which numbers around 10 where I have had to put muffs on.

I use this flusher...works awesome.
https://smile.amazon.com/gp/product/...?ie=UTF8&psc=1
I can not get the temp over 140° which is the temp of my thermostat.

There will always be water leaking around the muffs when the water volume is more than what the pump is pumping...that is a fact. You can't force water past the pump impeller. As I increase the engine RPM, the amount of water leaking around the muffs decrease until it goes down to close to zero when RPM is high enough. I know not to increase RPM past that.

I use the dual feed muffs on my Mercury outboard as well. In fact the dealer who I bought my pontoon boat with the Mercury outboard also used the dual feed muffs!

 

[Lou C]

http://www.volvopentastore.com/Lower...view_id.782033
So where is it?
I've seen an equal number in boatyards around here and the older SXs seem to have more small holes than a Cobra but no screen. The newer SXA yes I have seen a screen or removable screen design.

http://www.volvopentastore.com/Lower...view_id.792041
this is an SX M1, looks like the design changed...maybe that's when they added them....

What I am saying is that if you have a non removable screen design and the boat is kept in the water you will have a heck of time with marine growth in the water intakes. Inboards have a scoop with a hinge so it can be opened up and cleaned out, or the openings are big enough to clean it out and they will have a sea strainer inside the boat that can be cleaned out.
If you can't clean it out, you WILL have overheating, unless you are willing to split the drive and manually clean out the water intake area at least every 3 years. Removing the screen enabled me to clean it out with a stiff piece of wire with the boat on the mooring and the drive tilted all the way up.

 

[bruceb58]

LOL....Lou, why do you get so worked up every time the Volvo muffs topic comes up? The lower unit is different on the Volvo than the OMC. That's a fact. If you actually owned a Volvo you would know.

 

[bruceb58]

So I went to where my boat is stored. It doesn't really have a screen per se but has a casting right behind the inlet holes. No way you can put a thin rod all the way through to the other side. I put my flashlight up to one side and you can see zero light out the other side.

 

[Lou C]

Bruce all I am trying to say really is this:
I used to have great success with those muffs, but I tried two of them both bought new, one at West Marine and one at another marine shop and my formerly easy to prime Cobra would not prime with either. The rubber is just too stiff.

There is another Merc style that does not use the rod, if the rubber is the same they would work nearly as well I'd think.
You're lucky that you got a good set of the dual inlet ones...

The instructions that come with the Merc ones with the rod clamp say to just drill a 1/8th" hole through the lower unit to secure the rod. I can see people not wanting to do this of course. I just used the holes for the water intakes, since I removed the screen that was there.

With the water passage/screen issue, if you kept your boat in salt water you'd see what I'm talking about. Its a real pain, having that water passage get clogged up with barnacles every 2 years or so. Being the backyard mechanic that I am, I had to come up with an expedient solution. So far its resulted in an engine that runs at a nice cool 160 instead of 185 like before. One of the few adaptations you have to make if you want to keep a sterndrive in salt water. If I ever had an issue with seaweed, etc clogging it I'd adapt the removable screens that the later OMCs and some Volvos have. Because at least that can be removed and cleaned out without it becoming a project (ie splitting the drive). I have a trick for doing that too, after a few years in the salt they do not want to come apart so easy....

 

[bruceb58]

You're lucky that you got a good set of the dual inlet ones....

The only issue is that the plastic feeding the muff ears crack over time, otherwise they work well. I use to have the ones that just fed water from one side...they sucked.

 

[USA_boater]

Well I looked at my '04 SX drive and it has no visible screen and some casting right behind the inlet holes too. As mentioned before, I tried the dual inlet muffs and exchanged for single...perhaps I did wrong but luckily I won't have to use muffs again since the engine bay inlet port works. BUT, I'd swear when I used single muffs I still saw water escaping from the non-hose side which would tell me they are still priming well enough and the casting isn't totally blocking?

With either dual or single, the boat ran hotter than when using the engine bay port...but it didn't overheat with the single muffs so they must be "fine" for a Volvo out drive. I've also seen youtube vids of people using them on Volvos.

 

[bruceb58]

You are correct. The housing doesn't totally block the water. Both sides feed water up to the pivot housing passage.